US7907350B2 - Zoom lens system, imaging apparatus, method for zooming, and method for vibration reduction - Google Patents

Zoom lens system, imaging apparatus, method for zooming, and method for vibration reduction Download PDF

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US7907350B2
US7907350B2 US12/299,748 US29974807A US7907350B2 US 7907350 B2 US7907350 B2 US 7907350B2 US 29974807 A US29974807 A US 29974807A US 7907350 B2 US7907350 B2 US 7907350B2
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lens group
end state
refractive power
zoom lens
lens system
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US20090219619A1 (en
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Shinichi Mitsuki
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Nikon Corp
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Nikon Corp
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
    • G02B15/163—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group
    • G02B15/167—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses
    • G02B15/173—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group having an additional fixed front lens or group of lenses arranged +-+
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/145—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only
    • G02B15/1451—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being positive
    • G02B15/145113—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being positive arranged +-++-
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/64—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image
    • G02B27/646—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image compensating for small deviations, e.g. due to vibration or shake

Definitions

  • the present invention relates to a zoom lens system, an imaging apparatus, a method for zooming the zoom lens system, and a method for vibration reduction of the zoom lens system.
  • a camera such as an electronic still camera that outputs an object image by using an imaging device such as an electronic imaging device and stores it as a digital image has been mostly used.
  • electronic imaging devices have been miniaturized and highly integrated, so that even a highly integrated one has been available at a reasonable price.
  • a lens system installed in a camera using such an electronic imaging device has also been miniaturized.
  • a zoom lens system having a zoom ratio of about three composed of, in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, and a prism for bending an optical path being disposed in the first lens group (see Japanese Patent Application Laid-Open No. 2000-131640).
  • an optical-path-bending element for bending an optical path is disposed in a zoom lens system, in order to shorten the length of the zoom lens system in the depth direction, in other words, an incident light direction, it is most effective to dispose the optical-path-bending element in the first lens group.
  • the dimension of the zoom lens system in the depth direction can be further smaller.
  • the zoom lens system becomes a high zoom ratio
  • the lens diameter of the first lens group has to be large. Accordingly, the optical-path-bending element has to be large, so that the length in the depth direction cannot be reduced.
  • the conventional zoom lens system has made it possible to shorten the length in the depth direction by disposing an optical-path-bending element in the first lens group, the zoom ratio has been small, and the prism has not been sufficiently small.
  • the present invention is made in view of the aforementioned problems and has an object to provide a high optical performance zoo lens system with realizing a high zoom ratio and compactness suitable for a highly integrated electronic imaging device, an imaging apparatus, a method for zooming the zoom lens system, and a method for vibration reduction of the zoom lens system.
  • a zoom lens system comprising, in order from an object along an optical axis: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group having negative refractive power, upon zooming from a wide-angle end state to a telephoto end state, the second lens group and the fourth lens group being moved along the optical axis, the first lens group including, in order from the object along the optical axis, a front lens group having negative refractive power, an optical-path-bending element for bending an optical path, and a rear lens group having positive refractive power, and the following conditional expression (1) being satisfied: 0.75 ⁇ ( fw ⁇ ft ) 1/2 /( ⁇ fn 1) ⁇ 0.95 (1) where fw denotes a focal length of the zoom lens system in the wide-angle end state, ft denotes
  • a zoom lens system comprising, in order from an object along an optical axis: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group having negative refractive power, upon zooming from a wide-angle end state to a telephoto end state, the second lens group and the fourth lens group being moved along the optical axis, the first lens group including an optical-path-bending element for bending an optical path, and the third lens group being movable in a direction substantially perpendicular to the optical axis.
  • an imaging apparatus equipped with the zoom lens system according to the first aspect or the second aspect.
  • a method for zooming a zoom lens system comprising steps of: providing the zoom lens system including, in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power; providing the first lens group including, in order from the object along the optical axis, a front lens group having negative refractive power, an optical-path-bending element for bending an optical path, and a rear lens group having positive refractive power; satisfying the following conditional expression (1): 0.75 ⁇ ( fw ⁇ ft ) 1/2 /( ⁇ fn 1) ⁇ 0.95 (1) where fw denotes a focal length of the zoom lens system in the wide-angle end state, ft denotes a focal length of the zoom lens system in the telephoto end state, and fn1 denote
  • a method for zooming a zoom lens system comprising steps of: providing the zoom lens system including, in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power; providing the first lens group including an optical-path-bending element for bending an optical path; moving the third lens group in a direction substantially perpendicular to the optical axis; and moving the second lens group and the fourth lens group along the optical axis upon zooming from a wide-angle end state to a telephoto end state.
  • the present invention makes it possible to provide a high optical performance zoom lens system with realizing a high zoom ratio and compactness suitable for a highly integrated electronic imaging device, an imaging apparatus, a method for zooming the zoom lens system, and a method for vibration reduction of the zoom lens system.
  • FIG. 1 is a sectional view showing lens configuration of a zoom lens system according to Example 1 together with a zooming trajectory of each lens group.
  • FIGS. 2A , 2 B and 2 C are graphs showing various aberrations of the zoom lens system according to Example 1 upon focusing on an infinity object without performing vibration reduction, in which FIG. 2A is in a wide-angle end state, FIG. 2B is in an intermediate focal length state, and FIG. 2C is in a telephoto end state.
  • FIGS. 3A , 3 B and 3 C are graphs showing coma of the zoom lens system according to Example 1 upon focusing on an infinity object with vibration reduction, in which FIG. 3A is in a wide-angle end state, FIG. 3B is in an intermediate focal length state, and FIG. 3C is in a telephoto end state.
  • FIG. 4 is a sectional view showing lens configuration of a zoom lens system according to Example 2 together with a zooming trajectory of each lens group.
  • FIGS. 5A , 5 B and 5 C are graphs showing various aberrations of the zoom lens system according to Example 2 upon focusing on an infinity object without performing vibration reduction, in which FIG. 5A is in a wide-angle end state, FIG. 5B is in an intermediate focal length state, and FIG. 5C is in a telephoto end state.
  • FIGS. 6A , 6 B and 6 C are graphs showing coma of the zoom lens system according to Example 2 upon focusing on an infinity object with vibration reduction, in which FIG. 6A is in a wide-angle end state, FIG. 6B is in an intermediate focal length state, and FIG. 6C is in a telephoto end state.
  • FIG. 7 is a sectional view showing lens configuration of a zoom lens system according to Example 3 together with a zooming trajectory of each lens group.
  • FIGS. 8A , 8 B and 8 C are graphs showing various aberrations of the zoom lens system according to Example 3 upon focusing on an infinity object without performing vibration reduction, in which FIG. 8A is in a wide-angle end state, FIG. 8B is in an intermediate focal length state, and FIG. 8C is in a telephoto end state.
  • FIGS. 9A , 9 B and 9 C are graphs showing coma of the zoom lens system according to Example 3 upon focusing on an infinity object with vibration reduction, in which FIG. 9A is in a wide-angle end state, FIG. 9B is in an intermediate focal length state, and FIG. 9C is in a telephoto end state.
  • FIGS. 10A and 10B are diagrams showing a camera equipped with a zoom lens system according to present embodiment, in which FIG. 10A is a front view, and FIG. 10B is a rear view.
  • FIG. 11 is a sectional view along A-A line in FIG. 10A .
  • a zoom lens system, an imaging apparatus, a method for zooming the zoom lens system, and a method for vibration reduction of the zoom lens system according to the present embodiment are explained below.
  • a zoom lens system includes, in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power.
  • the first lens group includes, in order from the object along the optical axis, a front lens group having negative refractive power, an optical-path-bending element for bending an optical path at substantially 90 degrees, and a rear lens group having positive refractive power.
  • conditional expression (1) 0.75 ⁇ ( fw ⁇ ft ) 1/2 /( ⁇ fn 1) ⁇ 0.95 (1)
  • fw denotes a focal length of the zoom lens system in the wide-angle end state
  • ft denotes a focal length of the zoom lens system in the telephoto end state
  • fn1 denotes a focal length of the front lens group in the first lens group.
  • the zoom lens system In order to construct the zoom lens system to have a high zoom ratio, although it is effective to increase the number of lens groups or moving amount of each lens group, the zoom lens system becomes large, and the number of lenses composing the system becomes large. Accordingly, a camera equipped with such a zoom lens becomes large even in a so-called retracted state where the lens is accommodated in the camera, so that the camera becomes large.
  • a zoom lens system according to the present embodiment with disposing the optical-path-bending element in the first lens group as described above, it becomes possible to realize to shorten the length in the depth direction of the zoom lens system, and to narrow the lens barrel and the camera body.
  • the optical-path-bending element is necessary to become small.
  • the fifth lens group since the fifth lens group has negative refractive power, the total focal length of the lenses locating to the object side of the fifth lens group becomes small, so that the effective diameter can be small, and the optical-path-bending element can be compact.
  • Conditional expression (1) defines a focal length of the front lens group in the first lens group.
  • conditional expression (1) when the value is equal to or exceeds the upper limit of conditional expression (1), in other words, when refractive power of the front lens group becomes large, spherical aberration in the telephoto end state becomes worse.
  • conditional expression (1) it becomes possible to realize to construct the optical-path-bending element to be compact with excellently correcting various aberrations, so that the zoom lens system can be realized to be compact.
  • conditional expression (2) is preferably satisfied: 0.3 ⁇ f 1 /ft ⁇ 0.6 (2) where f1 denotes a focal length of the first lens group.
  • conditional expression (2) defines a relation between a focal length of the first lens group and that of the zoom lens system in the telephoto end state.
  • the first lens group, the third lens group, and the fifth lens group are fixed with respect to the image plane upon zooming from the wide-angle end state to the telephoto end state.
  • focusing from an infinity object to a close object is carried out by moving the fourth lens group to the object.
  • conditional expression (3) is preferably satisfied: 1.0 ⁇ T 5 ⁇ 1.5 (3) where ⁇ T5 denotes an imaging magnification of the fifth lens group upon focusing on an infinity object in the telephoto end state.
  • Conditional expression (3) defines an imaging magnification of the fifth lens group.
  • the focal length of the lens groups disposing to the object side of the fifth lens group becomes larger than the focal length of the zoom lens system. Accordingly, the optical-path-bending element becomes large, so that it becomes impossible to realize to construct the zoom lens system to be compact.
  • conditional expression (3) it is preferable to set the upper limit of conditional expression (3) to 1.4.
  • the fifth lens group preferably consists of one cemented lens.
  • the cemented lens may be constructed by three lenses or more.
  • variation in imaging position caused by a camera shake is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis.
  • a vibration reduction method carried out by decentering a portion of the lens system it is generally required that the amount of decentering is small and deterioration in optical performance upon vibration reduction is also extremely small.
  • the amount of decentering is made to be minimal.
  • the diameter has to be small, and chromatic aberration and spherical aberration have to be corrected.
  • a zoom lens system includes, in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power.
  • the second lens group and the fourth lens group are moved along the optical axis.
  • the first lens group includes an optical-path-bending element for bending an optical path. Variation in an imaging position caused by a camera shake is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis.
  • each light-sensitive element becomes minute, and the light amount received in each light-sensitive element becomes small, so that sensitivity becomes lower.
  • each pixel becomes minute, and the light amount received in each pixel becomes small, so that light sensitivity becomes lower.
  • the optical system has to be a large aperture ratio or the exposure time upon shooting has to be long.
  • the optical system naturally becomes large, so that the effect of making the imaging device compact is cancelled out. Accordingly, it is against the object of the invention.
  • a vibration reduction mechanism for correcting an image blur becomes indispensable to the optical system.
  • vibration reduction is carried out by moving the third lens group in a direction substantially perpendicular to the optical axis as described above.
  • a vibration reduction method correcting variation in the imaging position caused by a camera shake by decentering a portion of the optical system, it is required that decentered amount is small and deterioration in optical performance is extremely small.
  • the decentered lens group in other words, the vibration reduction lens group is required that the diameter thereof is small and chromatic aberration and spherical aberration thereof have to be corrected.
  • conditional expression (4) is preferably satisfied: 1.0 ⁇ (1- ⁇ 3 T ) ⁇ rT ⁇ 1.8 (4) where ⁇ 3T denotes an imaging magnification of the third lens group upon focusing on an infinity object in the telephoto end state, and ⁇ rT denotes a combined imaging magnification of lens groups disposing to the image side of the third lens group.
  • Conditional expression (4) defines a relation between the imaging magnification of the third lens group and combined imaging magnification of lens groups disposed to the image side of the third lens group, and shows decentering sensitivity of the third lens group.
  • conditional expression (5) is preferably satisfied: ⁇ 0.2 ⁇ 1/ ⁇ 3 T ⁇ 0.2 (5) where ⁇ 3T denotes an imaging magnification of the third lens group upon focusing on an infinity object in the telephoto end state.
  • Conditional expression (5) defines imaging magnification of the third lens group.
  • conditional expression (5) it is preferable to set the upper limit of conditional expression (5) to 0.1.
  • conditional expression (5) when a zoom lens system according to the present embodiment satisfies conditional expression (5), it becomes possible to prevent deterioration in optical performance upon decentering between the third lens group and the fourth lens group, and to accomplish high optical performance upon vibration reduction.
  • the first lens group includes, in order from the object along the optical axis, a front lens group having negative refractive power, an optical-path-bending element, and a rear lens group having positive refractive power, and the following conditional expression (1) is preferably satisfied: 0.75 ⁇ ( fw ⁇ ft ) 1/2 /( ⁇ fn 1) ⁇ 0.95 (1) where fw denotes a focal length of the zoom lens system in the wide-angle end state, ft denotes a focal length of the zoom lens system in the telephoto end state, and fn1 denotes a focal length of the front lens group in the first lens group.
  • conditional expression (2) is preferably satisfied: 0.3 ⁇ f 1 /ft ⁇ 0.6 (2) where f1 denotes a focal length of the first lens group.
  • the first lens group, the third lens group, and the fifth lens group are preferably fixed with respect to the image plane upon zooming from the wide-angle end state to the telephoto end state.
  • the drive system for driving these lens groups can be simple. Accordingly, the lens barrel can be compact, and electricity can be saved.
  • the fourth lens group is preferably moved along the optical axis upon focusing from an infinity object to a close object.
  • the number of movable lens group becomes only two, so that the drive mechanism for driving these lens groups can be simplified. Accordingly, the lens barrel can be compact, and electricity can be saved.
  • conditional expression (3) is preferably satisfied: 1.0 ⁇ T5 ⁇ 1.5 (3) where ⁇ T5 denotes an imaging magnification of the fifth lens group upon focusing on an infinity object in the telephoto end state.
  • the fifth lens group is preferably composed of one cemented lens.
  • the cemented lens may be constructed by three lenses or more.
  • An imaging apparatus is equipped with the zoom lens system explained above.
  • a method for zooming a zoom lens system comprising steps of: providing the zoom lens system including, in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power; providing the first lens group including, in order from the object along the optical axis, a front lens group having negative refractive power, an optical-path-bending element for bending an optical path, and a rear lens group having positive refractive power; satisfying the following conditional expression (1): 0.75 ⁇ ( fw ⁇ ft ) 1/2 /( ⁇ fn 1) ⁇ 0.95 (1) where fw denotes a focal length of the zoom lens system in the wide-angle end state, ft denotes a focal length of the zoom lens system in the telephoto end state, and fn1 denotes a focal length of the front lens group in
  • a method for vibration reduction of a zoom lens system comprising steps of: providing the zoom lens system including, in order from an object along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power; moving the second lens group and the fourth lens group along the optical axis upon zooming from a wide-angle end state to a telephoto end state; providing the first lens group including an optical-path-bending element for bending an optical path; and moving the third lens group in a direction substantially perpendicular to the optical axis for correcting variation in the imaging position caused by a camera shake.
  • FIG. 1 is a sectional view showing lens configuration of a zoom lens system according to Example 1 together with a zooming trajectory of each lens group.
  • the zoom lens system according to Example 1 is composed of, in order from an object along an optical axis, a first lens group G 1 having positive refractive power, a second lens group G 2 having negative refractive power, a third lens group G 3 having positive refractive power, a fourth lens group G 4 having positive refractive power, and a fifth lens group G 5 having negative refractive power.
  • the first lens group G 1 is composed of, in order from the object along the optical axis, a front lens group G 1 f having negative refractive power, a rectangular prism P for bending an optical path, and a rear lens group G 1 r having positive refractive power.
  • the front lens group G 1 f is composed of a negative meniscus lens L 11 having a concave surface facing an image.
  • the rear lens group G 1 r is composed of, in order from the object along the optical axis, a double convex positive lens L 12 , and a double convex positive lens L 13 having an aspherical surface facing the object.
  • the zoom lens system according to Example 1 has a lens configuration whose optical path is bent by the rectangular prism P at substantially 90 degrees as shown in FIG. 11 , the optical path is extended in FIG. 1 .
  • the second lens group G 2 is composed of, in order from the object along the optical axis, a double concave negative lens L 21 having an aspherical surface facing the image, and a cemented lens constructed by a double concave negative lens L 22 cemented with a double convex positive lens L 23 .
  • the third lens group G 3 is composed of, in order from the object along the optical axis, a double convex positive lens L 31 having an aspherical surface facing the image, and a cemented lens constructed by a double convex positive lens L 32 cemented with a double concave negative lens L 33 .
  • the fourth lens group G 4 is composed of a cemented lens constructed by, in order from the object along the optical axis, a negative meniscus lens L 41 having a concave surface facing the image cemented with a double convex positive lens L 42 having an aspherical surface facing the image.
  • the fifth lens group G 5 is composed of a cemented lens constructed by, in order from the object along the optical axis, a double convex positive lens L 51 cemented with a double concave negative lens L 52 .
  • An aperture stop S is disposed to the object side of the third lens group G 3 , and a low-pass filter FL for blocking spatial frequency higher than resolution limit of an imaging device (not shown) is disposed between the fifth lens group G 5 and the image plane I.
  • the zoom lens system upon zooming from a wide-angle end state to a telephoto end state, the second lens group G 2 is moved to the image, the fourth lens group is moved at first to the object and then to the image, and the first lens group G 1 , the third lens group G 3 and the fifth lens group G 5 are fixed with respect to the image plane I such that a distance between the first lens group G 1 and the second lens group G 2 increases, a distance between the second lens group G 2 and the third lens group G 3 decreases, and a distance between the third lens group G 3 and the fourth lens group G 4 varies.
  • variation in the imaging position caused by a camera shake is corrected by moving the third lens group G 3 in a direction substantially perpendicular to the optical axis.
  • W denotes the wide-angle end state
  • M denotes an intermediate focal length state
  • T denotes the telephoto end state
  • f denotes a focal length
  • FNO denotes an f-number
  • ⁇ denotes a half angle of view (maximum angle of incidence, unit: degree).
  • the first column “N” shows the lens surface number counted in order from the object side
  • the second column “R” shows a radius of curvature of the lens surface
  • the third column “D” shows a distance to the next surface
  • y denotes a vertical height from the optical axis
  • x denotes a sag amount which is a distance along the optical axis from the tangent surface at the vertex of the aspherical surface to the aspherical surface at the vertical height y from the optical axis
  • c denotes a curvature of a reference sphere (paraxial curvature)
  • ⁇ denotes a conical coefficient
  • C4, C6, . . . denote aspherical coefficients.
  • E ⁇ n denotes “ ⁇ 10 ⁇ n ”, for example, “1.234E ⁇ 0.05” denotes “1.234 ⁇ 10 ⁇ 5 ”.
  • mm is generally used for the unit of length such as the focal length, the radius of curvature and the like.
  • the unit is not necessarily to be limited to “mm”, and any other suitable unit can be used.
  • the explanation of reference symbols is the same in the other Examples.
  • FNO denotes an f-number
  • Y denotes an image height.
  • astigmatism a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane.
  • ⁇ denotes a correction angle in degrees upon vibration reduction.
  • the zoom lens system according to Example 1 shows superb optical performance as a result of good corrections to various aberrations in the wide-angle end state, in the intermediate focal length state, and in the telephoto end state.
  • FIG. 4 is a sectional view showing lens configuration of a zoom lens system according to Example 2 together with a zooming trajectory of each lens group.
  • the zoom lens system according to Example 2 is composed of, in order from an object along an optical axis, a first lens group G 1 having positive refractive power, a second lens group G 2 having negative refractive power, a third lens group G 3 having positive refractive power, a fourth lens group G 4 having positive refractive power, and a fifth lens group G 5 having negative refractive power.
  • the first lens group G 1 is composed of, in order from the object along the optical axis, a front lens group G 1 f having negative refractive power, a rectangular prism P for bending an optical path, and a rear lens group G 1 r having positive refractive power.
  • the front lens group G 1 f is composed of a negative meniscus lens L 11 having a concave surface facing an image.
  • the rear lens group G 1 r is composed of, in order from the object along the optical axis, a double convex positive lens L 12 , and a double convex positive lens L 13 having aspherical surfaces on both lens surfaces.
  • the zoom lens system according to Example 2 has a lens configuration whose optical path is bent by the rectangular prism P at substantially 90 degrees as shown in FIG. 11 , the optical path is extended in FIG. 4 .
  • the second lens group G 2 is composed of, in order from the object along the optical axis, a negative meniscus lens L 21 having a concave surface facing the image, and a cemented lens constructed by a double concave negative lens L 22 cemented with a double convex positive lens L 23 .
  • the third lens group G 3 is composed of, in order from the object along the optical axis, a double convex positive lens L 31 having an aspherical surface facing the image, and a cemented lens constructed by a double convex positive lens L 32 cemented with a double concave negative lens L 33 .
  • the fourth lens group G 4 is composed of a cemented lens constructed by, in order from the object along the optical axis, a negative meniscus lens L 41 having a concave surface facing the image cemented with a double convex positive lens L 42 having an aspherical surface facing the image.
  • the fifth lens group G 5 is composed of a cemented lens constructed by, in order from the object along the optical axis, a double concave negative lens L 51 cemented with a double convex positive lens L 52 .
  • An aperture stop S is disposed to the object side of the third lens group G 3 , and a low-pass filter FL for blocking spatial frequency higher than resolution limit of an imaging device (not shown) is disposed between the fifth lens group G 5 and the image plane I.
  • the zoom lens system according to Example 2 upon zooming from a wide-angle end state to a telephoto end state, the second lens group G 2 is moved to the image, the fourth lens group is moved at first to the object and then to the image, and the first lens group G 1 , the third lens group G 3 and the fifth lens group G 5 are fixed with respect to the image plane I such that a distance between the first lens group G 1 and the second lens group G 2 increases, a distance between the second lens group G 2 and the third lens group G 3 decreases, and a distance between the third lens group G 3 and the fourth lens group G 4 varies.
  • variation in the imaging position caused by a camera shake is corrected by moving the third lens group G 3 in a direction substantially perpendicular to the optical axis.
  • the zoom lens system according to Example 2 shows superb optical performance as a result of good corrections to various aberrations in the wide-angle end state, in the intermediate focal length state, and in the telephoto end state.
  • FIG. 7 is a sectional view showing lens configuration of a zoom lens system according to Example 3 together with a zooming trajectory of each lens group.
  • the zoom lens system according to Example 3 is composed of, in order from an object along an optical axis, a first lens group G 1 having positive refractive power, a second lens group G 2 having negative refractive power, a third lens group G 3 having positive refractive power, a fourth lens group G 4 having positive refractive power, and a fifth lens group G 5 having negative refractive power.
  • the first lens group G 1 is composed of, in order from the object along the optical axis, a front lens group G 1 f having negative refractive power, a rectangular prism P for bending an optical path, and a rear lens group G 1 r having positive refractive power.
  • the front lens group G 1 f is composed of a negative meniscus lens L 11 having a concave surface facing an image.
  • the rear lens group G 1 r is composed of, in order from the object along the optical axis, a double convex positive lens L 12 having an aspherical surface facing the image, and a double convex positive lens L 13 .
  • the zoom lens system according to Example 3 has a lens configuration whose optical path is bent by the rectangular prism P at substantially 90 degrees as shown in FIG. 11 , the optical path is extended in FIG. 7 .
  • the second lens group G 2 is composed of, in order from the object along the optical axis, a double concave negative lens L 21 having an aspherical surface facing the image, and a cemented lens constructed by a double concave negative lens L 22 cemented with a double convex positive lens L 23 .
  • the third lens group G 3 is composed of, in order from the object along the optical axis, a double convex positive lens L 31 having an aspherical surface facing the image, and a cemented lens constructed by a double convex positive lens L 32 cemented with a double concave negative lens L 33 .
  • the fourth lens group G 4 is composed of a cemented lens constructed by, in order from the object along the optical axis, a negative meniscus lens L 41 having a concave surface facing the image cemented with a double convex positive lens L 42 having an aspherical surface facing the image.
  • the fifth lens group G 5 is composed of a cemented lens constructed by, in order from the object along the optical axis, a positive meniscus lens L 51 having a convex surface facing the image cemented with a negative meniscus lens L 52 having a concave surface facing the object.
  • An aperture stop S is disposed to the object side of the third lens group G 3 , and a low-pass filter FL for blocking spatial frequency higher than resolution limit of an imaging device (not shown) is disposed between the fifth lens group G 5 and the image plane I.
  • the zoom lens system according to Example 3 upon zooming from a wide-angle end state to a telephoto end state, the second lens group G 2 is moved to the image, the fourth lens group is moved at first to the object and then to the image, and the first lens group G 1 , the third lens group G 3 and the fifth lens group G 5 are fixed with respect to the image plane I such that a distance between the first lens group G 1 and the second lens group G 2 increases, a distance between the second lens group G 2 and the third lens group G 3 decreases, and a distance between the third lens group G 3 and the fourth lens group G 4 varies.
  • variation in the imaging position caused by a camera shake is corrected by moving the third lens group G 3 in a direction substantially perpendicular to the optical axis.
  • the zoom lens system according to Example 3 shows superb optical performance as a result of good corrections to various aberrations in the wide-angle end state, in the intermediate focal length state, and in the telephoto end state.
  • each Example of the present embodiment makes it possible to realize a high optical performance zoom lens system with a high zoom ratio and compactness suitable for a highly integrated electronic imaging device.
  • zoom lens system with a five-lens-group configuration is shown as each Example of the present application, the present application is not limited to this, and is applicable to the other lens configurations such as a six-lens-group configuration, and a seven-lens-group configuration.
  • a portion of a lens group, a lens group, or a plurality of lens groups may be moved along an optical axis as a focusing lens group.
  • the focusing lens group may be used for auto focus, and is suitable for being driven by a motor such as an ultrasonic motor.
  • any lens surface may be an aspherical surface.
  • the aspherical surface may be fabricated by a fine grinding process, a glass molding process that a glass material is formed into an aspherical shape by a mold, or a compound type process that a resin material is formed into an aspherical shape on a glass surface.
  • An antireflection coating having high transmittance over a broad wavelength range may be applied to each lens surface of a zoom lens system according to the present application to reduce flare or ghost images, so that high optical performance with a high contrast can be attained.
  • FIGS. 10A and 10B are diagrams showing an electronic still camera equipped with the zoom lens system according to the present embodiment, in which FIG. 10A is a front view, and FIG. 10B is a rear view.
  • FIG. 11 is a sectional view along A-A line in FIG. 10A .
  • the camera 1 is an electronic still camera equipped with the zoom lens system according to Example 1 as a photo-taking lens 2 as shown in FIGS. 10A , 10 B, and 11 .
  • an electronic still camera 1 when a power switch button (not shown) is pressed, a shutter (not shown) is opened. Accordingly, light from an object (not shown) is incident on the image-taking lens 2 , deflected by a rectangular prism P in the image-taking lens 2 at substantially 90 degrees as shown in FIG. 11 , and an image is formed on an imaging device C disposed on an image plane I. The object image formed on the imaging device C is captured and displayed on a liquid crystal monitor 3 disposed backside of the electronic still camera 1 .
  • a photographer After fixing the composition of the object image with observing the liquid crystal monitor 3 , a photographer depresses a release button 4 to take a picture of the object image by the imaging device C, and stores in a memory (not shown). In this manner, the photographer can take a picture of the object by the camera 1 .
  • the following members are disposed such as an auxiliary light emitter 5 that emits auxiliary light when the object is dark, a W-T button 6 that makes the zoom lens system carry out zooming from a wide-angle end state (W) to a telephoto end state (T), and a function button 7 that is used for setting various conditions of the electronic still camera 1 .
  • a zoom lens system according to Example 1 installed in the camera 1 as an image-taking lens 2 having the specific lens configuration as described above in Example 1 makes it possible to provide a high optical performance zoom lens system with a high zoom ratio and compactness suitable for a highly integrated electronic imaging device. Accordingly, the camera 1 is suitable for a highly integrated electronic imaging device and makes it possible to accomplish a high zoom ratio and compactness.
  • the present embodiment can provide a zoom lens system, an imaging apparatus, a method for zooming the zoom lens system, and a method for vibration reduction of the zoom lens system.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Lenses (AREA)
  • Adjustment Of Camera Lenses (AREA)
  • Studio Devices (AREA)
US12/299,748 2006-07-27 2007-07-25 Zoom lens system, imaging apparatus, method for zooming, and method for vibration reduction Expired - Fee Related US7907350B2 (en)

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JP2006-205035 2006-07-27
JP2006205035A JP4929903B2 (ja) 2006-07-27 2006-07-27 ズームレンズ、撮像装置、ズームレンズの変倍方法
PCT/JP2007/065029 WO2008013307A1 (fr) 2006-07-27 2007-07-25 Objectif à focale variable, dispositif imageur, procédé de variation du grossissement d'un objectif à focale variable et procédé de stabilisation d'un objectif à focale variable

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JP5333903B2 (ja) * 2008-10-09 2013-11-06 株式会社ニコン ズームレンズ、これを搭載する光学機器
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JP5714925B2 (ja) * 2011-01-31 2015-05-07 ソニー株式会社 インナーフォーカス式レンズ
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JP6364613B2 (ja) * 2014-04-25 2018-08-01 パナソニックＩｐマネジメント株式会社 ズームレンズ系、撮像装置
CN107087109A (zh) * 2017-05-23 2017-08-22 努比亚技术有限公司 一种拍照调节终端及方法
JP6947217B2 (ja) * 2017-09-11 2021-10-13 株式会社ニコン 変倍光学系、光学装置、および変倍光学系の製造方法
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WO2008013307A1 (fr) 2008-01-31
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US20090219619A1 (en) 2009-09-03

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